A5048108463- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Gaussian Processes and Bayesian Inference
- Scientific Research and Discoveries
- Statistical and numerical algorithms
- Real-time simulation and control systems
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- AI in cancer detection
- Air Quality Monitoring and Forecasting
- Neural Networks and Applications
- Particle physics theoretical and experimental studies
- Astrophysics and Cosmic Phenomena
- solar cell performance optimization
- Advanced Measurement and Metrology Techniques
- History and Developments in Astronomy
- Electromagnetic Compatibility and Measurements
- Traffic Prediction and Management Techniques
- Spectroscopy and Chemometric Analyses
University of California, Riverside
2020-2025
University of Michigan
2025
Center for Theoretical Physics
2025
National Central University
2022
National Taiwan University
2016
Laboratory Imaging (Czechia)
2005
American Society of Echocardiography
2005
National Chung Cheng University
2004
Abstract Primordial black holes (PBHs) could explain some fraction of dark matter and shed light on many areas early-Universe physics. Despite over half a century research interest, PBH population has so far eluded detection. The most competitive constraints the comprised PBHs ( f DM ) in (10 −9 –10) M ⊙ mass ranges come from photometric microlensing bound ≲ 10 −2 –10 −1 . With advent Roman Space Telescope with its submilliarcsecond astrometric capabilities planned Galactic Bulge Time Domain...
Abstract We present new cosmological parameter constraints from the eBOSS Lyman-α forest survey. use a theoretical model and likelihood based on PRIYA simulation suite. is first suite to resolve Lyman- α in (120 Mpc/h) 3 volume, using multi-fidelity emulation technique. predict observables with ≲ 1% interpolation error over an 11 dimensional (9 simulated, 2 post-processing) space. identify internal tension within flux power spectrum data. Once discrepant data removed, we find primeval scalar...
Abstract From the formation mechanisms of stars and compact objects to nuclear physics, modern astronomy frequently leverages surveys understand populations answer fundamental questions. The population dark isolated in Galaxy contains critical information related many these topics, but is only practically accessible via gravitational microlensing. However, photometric microlensing observables are degenerate for different types lenses, one can seldom classify an event as involving either a...
Abstract There are expected to be millions of isolated black holes in the galaxy resulting from deaths massive stars. Measuring abundance and properties this remnant population would shed light on end stages stellar evolution paths hole systems. Detecting is currently only possible via gravitational microlensing, which has so far yielded one definitive detection. The difficulty finding microlensing lies having choose a small subset events, based characteristics their curves, allocate...
We present a new catalogue of Damped Lyman-$\alpha$ absorbers from SDSS DR16Q, as well estimates their statistical properties. Our are computed with the Gaussian process models presented in Garnett et al. (2017); Ho (2020) an improved model for marginalising uncertainty mean optical depth each quasar. compute column density distribution function (CDDF) at $2 < z 5$, line ($\textrm{d} N/ \textrm{d} X$), and neutral hydrogen ($\Omega_{\textrm{DLA}}$). provides posterior probability number DLAs...
We present methods for emulating the matter power spectrum by combining information from cosmological $N$-body simulations at different resolutions. An emulator allows estimation of simulation output interpolating across parameter space a limited number simulations. first implementation in cosmology multi-fidelity emulation, where many low-resolution are combined with few high-resolution to achieve an increased emulation accuracy. The spectrum's dependence on is learned simulations, which...
Abstract We present the PRIYA suite of cosmological simulations, based on code and hydrodynamic model ASTRID simulation, designed for analyses Lyman- α forest. Our simulation spans a 9-dimensional parameter space, including 4 parameters 5 astrophysical/thermal parameters. have run 48 low fidelity simulations with 1536 3 particles in 120 Mpc/h box high 3072 box. All our include full physics galaxy formation, supernova AGN feedback, thus also contain realistic population DLAs. advance earlier...
We make forecasts for the constraining power of 1D wavelet scattering transform when used with a Lyman-$\ensuremath{\alpha}$ forest cosmology survey. Using mock simulations and Fisher matrix, we show that there is considerable cosmological information in coefficients not captured by flux spectrum. estimate covariance matrices assuming uncorrelated Gaussian pixel noise each quasar at level drawn from simple log-normal model. The extra comes smaller estimated first-order second-order probe...
We present a revised version of our automated technique using Gaussian processes (GPs) to detect Damped Lyman-$\alpha$ absorbers (DLAs) along quasar (QSO) sightlines. The main improvement is allow process pipeline multiple DLAs single sightline. Our DLA detections are regularised by an improved model for the absorption from forest which improves performance at high redshift. also introduce unresolved sub-DLAs reduces mis-classifications without detectable damping wings. compare results those...
In this work we extend our recently developed multi-fidelity emulation technique to the simulated Lyman-$\alpha$ forest flux power spectrum. Multi-fidelity allows interpolation of simulation outputs between cosmological parameters using many cheap low-fidelity simulations and a few expensive high-fidelity simulations. Using test suite small box (30 Mpc/h) simulations, show that is able reproduce spectrum well, achieving an average accuracy when compared $0.8\%$. We further it has...
We present the PRIYA suite of cosmological simulations, based on code and hydrodynamic model ASTRID simulation, designed for analyses Lyman-$\alpha$ forest. Our simulation spans a $9$-dimensional parameter space, including $4$ parameters $5$ astrophysical/thermal parameters. have run $48$ low fidelity simulations with $1536^3$ particles in $120$ Mpc/h box $3$ high $3072^3$ box. All our include full physics galaxy formation, supernova AGN feedback, thus also contain realistic population DLAs....
Recently, fractal analyses have been applied successfully for the image compression, texture analysis and segmentation. The dimension could be used to quantify information. Several methods including box-counting, Brownian motion, iterative function system etc. can estimate dimension. In this study, differences of gray value neighboring pixels are an ultrasound breast lesion by using motion. Further, a computer-aided diagnosis based on is proposed classify lesions into two classes benign...
ABSTRACT We assemble the largest C iv absorption line catalogue to date, leveraging machine learning, specifically Gaussian processes, remove need for visual inspection detecting absorbers. The contains probabilities classifying reliability of system within a quasar spectrum. Our training set was sub-sample DR7 spectra that had no detectable in large visually inspected catalogue. used Bayesian model selection decide between our continuum and absorption-line models. Using random hold-out...
Primordial Black Holes (PBHs) could explain some fraction of dark matter and shed light on many areas early-universe physics. Despite over half a century research interest, PBH population has so far eluded detection. The most competitive constraints the comprised PBHs ($f_{\rm DM}$) in $(10^{-9}-10)M_{\odot}$ mass-ranges come from photometric microlensing bound $f_{\rm DM}\lesssim10^{-2}-10^{-1}$. With advent Roman Space Telescope with its sub-milliarcsecond (mas) astrometric capabilities...
ABSTRACT We develop an automated technique to measure quasar redshifts in the Baryon Oscillation Spectroscopic Survey of Sloan Digital Sky (SDSS). Our is extension earlier Gaussian process method for detecting damped Lyman α absorbers (DLAs) spectra with known redshifts. apply this a subsample SDSS DR12 BAL quasars removed and redshift larger than 2.15. show that we are broadly competitive existing estimators, disagreeing PCA by more 0.5 only $0.38{{\ \rm per\ cent}}$ spectra. produces...
We present new cosmological parameter constraints from the eBOSS Lyman-$\alpha$ forest survey. use a theoretical model and likelihood based on PRIYA simulation suite. is first suite to resolve in ($120$~Mpc/h~)$^3$ volume, using multi-fidelity emulation technique. predict observables with $\lesssim 1\%$ interpolation error over an $11$ dimensional ($9$ simulated, $2$ post-processing) space. identify internal tension within flux power spectrum data. Once discrepant data removed, we find...
ABSTRACT We introduce MF-Box, an extended version of MFEmulator, designed as a fast surrogate for power spectra, trained using N-body simulation suites from various box sizes and particle loads. To demonstrate MF-Box’s effectiveness, we design that include low-fidelity (LF) (L1 L2) at 256 $100 \, \rm {Mpc\, ~}h^{-1}$, each with 1283 particles, high-fidelity (HF) suite 5123 particles $256 representing higher load compared to the LF suites. MF-Box acts probabilistic resolution correction...
We make forecasts for the constraining power of 1D Wavelet Scattering Transform (WST) in context Lyman-$\alpha$ forest cosmology. Using mock simulations and a Fisher matrix, we show that there is considerable cosmological information scattering transform coefficients. estimate covariance matrices assuming uncorrelated Gaussian pixel noise each quasar, at level drawn from simple lognormal model. The extra comes smaller estimated first-order wavelet power, second-order coefficients which probe...
We introduce a population model to analyze the mixing between hypothesised power-law and $\sim 35 M_\odot$ Gaussian bump black hole populations in latest gravitational wave catalog, GWTC-3, estimating their co-location separation. find relatively low level of mixing, $3.1^{+5.0}_{-3.1}\%$, populations, compared percentage mergers containing two holes, $5.0^{+3.2}_{-1.7}\%$. Our analysis indicates that holes within are generally separate from population, with only minor fraction engaging...
There are expected to be millions of isolated black holes in the Galaxy resulting from death massive stars. Measuring abundance and properties this remnant population would shed light on end stages stellar evolution paths hole systems. Detecting is currently only possible via gravitational microlensing which has so far yielded one definitive detection. The difficulty finding lies having choose a small subset events based characteristics their lightcurves allocate expensive scarce follow-up...
The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is a co-planar interferometer array operating at wavelength of 3mm to measure the Sunyaev-Zeldovich effect (SZE) galaxy clusters. In first phase operation -- with compact 7-element 0.6m antennas (AMiBA-7) we observed six clusters angular scales from 5\arcmin 23\arcmin. Here, describe expansion AMiBA 13-element 1.2m (AMiBA-13), its subsequent commissioning, and our cluster SZE observing program. most important changes...
Cosmic microwave background (CMB) temperature anisotropies encode the history of universe, which manifest itself in angular power spectrum. We test spectra small patches from ESA $\textit{Planck}$ data. Known variations reveal informative details such as gravitational lensing and Doppler boosting effect. compute relative shifts via comparing selected randomly CMB. visualize on a full-sky HEALPix grid (a feature map) analyze statistical properties map. find regions contain Cold Spot Draco...